Aerodynamic motorcar



Oct. 11, 1960 H. BLASER 2,955,869

AERODYNAMIC MOTORCAR Filed Nov. 26, 1956 Figi INV EN TOR. HANS BLASER AT TO [2M EYS United States Patent Ofiice 2,955,869 Patented Oct. 11, 1960 AERODYNAMIC MOTORCAR Hans Blaser, 63 Rte. Chene, Geneva, Switzerland Filed Nov. 26, 1956, Ser. No. 624,399

Claims priority, application Switzerland Nov. '30, 1955 1 Claim. (Cl. 2961) In automobile-body design it is of primary importance to find a shape which has a low drag coefficient, which is of particular interest for high-speed motorcars, as the drag increases with the square of the speed.

Modern automobile bodies mostly are of streamline shape in which in most cases the frontmost and the hindmost points of the cowling are positioned near the bumpers which are disposed at rather low levels. The car bottom often is curved upwardly on both broadsides so that the air to be displaced by the car partly passes along the car head and partly is displaced to both sides of the car. There are some racing cars, however, in which a portion of the air to be displaced is conducted at the bow below the car bottom from where, however, it escapes at once sidewards on account of the lateral camber. The technical literature also points in this direction, for example on page 177 of the book Aerodynamics of Motorcars by R. Koenig-Fachsenfeld, volume II, it is said: The car bow has to be designed so that it raises most of the air above the car and does not depress same underneath the car.

Such cars often do not cling to the road to such an extent as is necessary in fast driving, and for this reason it has been attempted to improve the road-holding capacity by providing one or more rear fins. Such attempts, however, did not prove quite satisfactory.

I have found the cause for this unfavorable behaviour in the fact that such cars at high speeds are subjected to a certain lift, since they possess a corresponding lift coeflicient. When driving at high speeds, such lift relieves the wheels quite substantially so that the car bears on the road with a much smaller weight. Such lift becomes dangerous when braking, driving over curves and when overtaking other cars, as in such cases centrifugal forces arise which are proportional to the mass of the car. Said forces are not changed by the lift, so that they increase with the square of the speed, while at the same time the weight-decreasing lift increases whereby the road-holding capacity is rapidly lowered.

- The main object of my present invention is to eliminate these deficiencies by designing the car body or cowling differently, i.e. so that the lift is reduced to a minimum or eliminated altogether. An even better result is obtained, of course, by virtue of a body shape of which the lift coefiicient is negative, that is a shape in the case of which the air currents passing under the car are narrowed, whereby, according to the aerodynamic principle, known as the Venturi effect, a downwardly directed suction is produced. Such additional pressure obviously may increase the drag coefficient to some extent,

but this is more than compensated by the increased safety feature, in particular when driving through curves.

To attain the above-mentioned object, the motorcar according to the present invention is characterized by the fact that it comprises a bottom with a smooth underside and without projecting portions, said underside being cambered upwardly in front and so designed that in each section which is perpendicular to the driving direction no point of the bottom underside is at a lower level than the two marginal points in order to pass as much as possible of the air to be displaced rearwardly below the car bottom and not above the car nor sidewards thereof.

Thus, an important object of the present invention is to provide a vehicle body having a smooth and uninterrupted undersurface with the undersurface being devoid of depending and projecting elements and being transversely concave along the vehicles longitudinal axis with the transverse concave cross-sections in the immediate regions of the front and rear axles being displaced from the ground surface at a height less than the height of the cross-sections in the regions of the rear, center and front portions of the'bodys undersurface.

The foregoing and ancillary objects are attained by this invention, the preferred embodiment of which is set forth in the accompanying drawing, wherein;

Figure 1 is a schematic longitudinal elevational view of the vehicle body of the present invention, and,

Figure 2 is a schematic transverse view of the vehicle body.

As shown in the accompanying drawings, the surface motor vehicle includes a body it that has a smooth and uninterrupted undersurface 12. The undersurface 12 is devoid of dependent and projecting elements and is transversely concave along the vehicles longitudinal axis. The undersurface is formed so that in any vertical cross-section of the body no portion of the undersurface is disposed at a lower level than the side marginal points 14 and 16, as shown in Figure 2.

The transverse concave cross-sections uniformly vary in height relative to the ground surface along the vehicles longitudinal axis and, in this respect, the transverse concave cross-sections in the immediate regions of the front and rear axles 13 and 20, respectively, are displaced from the ground surface at a height less than the height of the cross sections in the regions of the rear portion 22, the center portion 24 and the front portion 26 of the bodys undersurface. Thus, the undersurface uniformly diverges outwardly from the regions of the front and rear axles so that the cross-sectional area perpendicular to the vehicles longitudinal axis and formed between the bodys undersurface and the ground surface 28 at the region of the rear front axles 18 and 20 is less than at any other portion of the undersurface to provide points of low pressure relative to the rest of the undersurface during vehicle operation.

I claim:

In a surface motor vehicle, a vehicle body having a smooth and uninterrupted undersurface, said undersurface being devoid of dependent and projecting elements, and being transversely concave along the vehicles longitudinal axis, and being so formed that in any vertical cross-section of the body, no portion of the undersurface is disposed at a lower level than the side marginal points thereof, said transverse'concave cross-sections uniformly varying in height relative to the ground surface along the vehicles longitudinal axis, said transverse concave cross-sections in the immediate regions of the front and rear axles being displaced from the ground surface at a height less than the height of the cross-sections in the regions of the rear, center and front portions of the bodys undersurface, whereby the undersurface uniformly diverges outwardly from theregions of the front and rear axles so thatthe cross-sectional area perpendicular to-the vehicles longitudinal axis and formed between thebodys undersurface and the ground surface at the References Cited in the file of this patent UNITED STATES PATENTS Best Aug. 16, 1938 McInnis Sept. 27, 1955 OTHER REFERENCES 7 The Automobile Engineer, September 1928, page 330, 

